U.S. patent number 7,295,320 [Application Number 10/999,532] was granted by the patent office on 2007-11-13 for detector arrangement based on surfaces plasmon resonance.
This patent grant is currently assigned to Gyros AB. Invention is credited to Tomas Agren, Lars Eriksson, Magnus Ljungstrom, Henrik Ostlin.
United States Patent |
7,295,320 |
Ostlin , et al. |
November 13, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Detector arrangement based on surfaces plasmon resonance
Abstract
A detector arrangement, which comprises a rotatable microfluidic
disc and a spectrophotometric detector unit. The arrangement is
characterized in that the detector unit is based on surface plasmon
resonance (SPR) and is capable of measuring an analyte within the
detection microcavities, each of which is part of a microchannel
structure. A microfluidic disc having an axis of symmetry and
comprising microchannel structures, each of which has an upstream
functional part that is at a shorter radial position than a
downstream functional part. The disc is characterized in that there
are detection microcavities (DMCs) in at least a part of said
microchannel structures, and that each of said DMCs has an SPR
surface on an inner wall and a detection detection window extending
from the SPR surface to the surface of the disc. The use of the
detector arrangement and microfluidic disc described above for
determining: a) if the content in one or more of the DMCs is a
liquid or a solid state or a gas, and/or b) a feature of an analyte
that may be present in a liquid which is present in one or more of
the DMCs.
Inventors: |
Ostlin; Henrik (Uppsala,
SE), Eriksson; Lars (Haninge, SE),
Ljungstrom; Magnus (Uppsala, SE), Agren; Tomas
(Uppsala, SE) |
Assignee: |
Gyros AB (Uppsala,
SE)
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Family
ID: |
29714430 |
Appl.
No.: |
10/999,532 |
Filed: |
November 30, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050179901 A1 |
Aug 18, 2005 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/SE03/00876 |
May 28, 2003 |
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60385179 |
May 31, 2002 |
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Foreign Application Priority Data
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May 31, 2002 [SE] |
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0201657 |
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Current U.S.
Class: |
356/445 |
Current CPC
Class: |
B01L
3/502715 (20130101); G01N 21/07 (20130101); G01N
21/253 (20130101); G01N 21/553 (20130101); B01L
2300/0654 (20130101); B01L 2300/0803 (20130101); B01L
2300/0806 (20130101); B01L 2400/0409 (20130101); G01N
21/554 (20130101); G01N 35/00069 (20130101) |
Current International
Class: |
G01N
21/55 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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11-304693 |
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Nov 1999 |
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JP |
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WO-0046589 |
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Aug 2000 |
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WO |
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WO-03102559 |
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Dec 2003 |
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WO |
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Other References
US. Appl. No. 10/867,893, Derand et al. cited by other .
Nagata et al., "Real-Time Analysis of Biomolecular Interactions,"
Chapter 1 & 2, Springer-Verlag Tokyo, 2000. cited by
other.
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Primary Examiner: Toatley, Jr.; Gregory J.
Assistant Examiner: Valentin, II; Juan D
Attorney, Agent or Firm: Fulbright & Jaworski, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of International Application
PCT/SE03/00876 filed May 28, 2003 and claims priority to U.S.
Provisional Application No. 60/385,179 filed on May 31, 2002 and
Swedish application No. 0201657.4, each of which is incorporated
herein in its entirety.
Claims
The invention claimed is:
1. A detector arrangement comprising: a) a rotary member having an
axis of rotation, said member comprises: (i) one or more
microfluidic discs, each disc comprises a plurality of essentially
equal and enclosed microchannel structures which are designed for
permitting liquid transport by centrifugal force created by
spinning the disc around the axis of rotation, and a first
plurality of surface plasmon resonance measuring cells (SPR-MCs),
each SPR-MCs comprises a detection microcavity (DMC), wherein an
SPR surface in an inner wall of the DMC and at least a part (P1) of
a detection window (DW) that stretches from the SPR surface to an
outer surface of the disc, and said outer surface of P1 for all
SPR-MCs are at the same radial distances (ii) a rotatable disc
holder comprising the remaining part (P2) of each of the DWs, b) a
non-rotatable SPR detector comprising (i) a light source (LS), and
(ii) a light detecting subunit (LDS), c) a beam path comprising (i)
an incident beam path (ibp) going from LS to one of the SPR
surfaces via the DW associated with this SPR surface, and (ii) a
reflected beam path (rpb) going from the same SPR surface to LDS
via said DW, the SPR-MCs being interchangeable by rotating said
rotatory member.
2. The arrangement of claim 1, wherein each DW is fully integrated
with each disc.
3. The arrangement of claim 1, wherein the DWs and the disc holder
are present at the same side of the microfluidic disc.
4. The arrangement of claim 3, wherein (a) P1 and P2 of each of the
DWs are connected to each other via an opto interface, and (b) ibp
and rbp are capable of passing through both of said parts for each
SPR-MC by rotating the rotary member.
5. The arrangement of claim 4, wherein said opto interface for each
DW is present in an opto interface plate that is placed between the
microfluidic disc and the disc holder.
6. The arrangement of claim 4, wherein (a) P2 for each DW is part
of a separate plate that is a part of the disc holder, and (b) the
disc is resting on top of this plate, said separate plate is made
of glass.
7. The arrangement of claim 3, wherein ibp reaches and/or rpb path
for each SPR-MC leaves the DW via one or more openings in the disc
holder.
8. The detector arrangement of claim 1, wherein the DWs and the
disc holder are on the opposite sides of the microfluidic disc.
9. The detector arrangement of claim 1, wherein said SPR detector
and said rotary member are laterally movable relative to each
other.
10. The arrangement of claim 9, wherein each microfluidic disc
comprises a second plurality of SPR-MCs that are located at radial
distances that are different from the radial distances of said
first plurality.
11. The arrangement of claim 1, wherein the breadth of a light beam
passing through the beam paths is less than the dimension of each
of the SPR surfaces and its underlying detection chamber.
12. The arrangement claim 1, wherein at least a part of the SPR-MCs
including the SPR surfaces and detection windows is arranged
annularly as one or more concentric circles around the axis of
symmetry.
13. The arrangement of claim 1, wherein at least a part of the
SPR-MCs including the SPR surfaces and detection windows is in a
spoke arrangement.
14. The arrangement of claim 1, wherein P1 for each of the DWs is
made in plastic material having a refractive index within the range
of 1.45-1.55.
15. The detector arrangement of claim 1, wherein each of the
microcavities are part of a microchannel structure that may be the
same or different for different microcavities.
16. The detector arrangement of claim 1, wherein the surfaces at
the entrance and the exit for ibp and rpb, respectively, are
essentially perpendicular to the optical axis of the incident and
reflected light.
17. The detector arrangement of claim 1, wherein each DW is
delineated by a prism surface at each of the entrance and exit of
light.
18. The detector arrangement of claim 1, wherein subpressure
retains the microfluidic disc in the disc holder.
Description
TECHNICAL FIELD
The present invention concerns a detector arrangement, which
comprises a detector unit, a rotatable microfluidic disc and means
for appropriately scanning the surface of the disc in order to
detect one or more substances that are present in detection
microcavities (DMCs) that are present within the disc. The
expression "to detect substances" includes detecting events taking
place in one or more of the DMCs.
The DMCs are parts of microchannels structures that are present in
the microfluidic disc. Liquid aliquots are transported and
processed in the microchannel structures.
The detection principles utilized to detect substances in
rotatable/spinnable microfluidic discs typically have been based on
spectrometric methods. The principles mainly have been adapted for
monitoring the results of the processing of liquids within
microfluidic discs and for relating such results to one or more
features of analytes. Typical features have been concentration,
qualitative aspect such as affinity, structure, etc.
BACKGROUND OF THE INVENTION
In the context of the present invention SPR stands for Surface
Plasmon Resonance as it is defined under the heading "SPR detector
unit". See below. Undefined or other variants of SPR have been
referred to in U.S. Pat. Nos. 6,338,820 and 5,994,150.
U.S. Pat. No. 5,994,150 (Imation Corp) describes an optical
assaying system utilizing a rotatable disc with multiple sensing
regions. The disc contains no detection microcavities or
microchannel structures in which liquid flow is able to transport
various reactants.
U.S. Pat. No. 6,338,820 (Alexion) describes an apparatus for
performing a plurality of assays in a rotatable circular disc
containing a plurality of concentrically arranged reaction sites.
Certain variants of the disc may be microfluidic in the sense that
the disc may have dispersion points for liquid that are connected
via channels to the reaction sites. The assays contemplated are
illustrated with chemical assays, biochemical reactions, cellular
assays, physical assays, biophysical assays etc which then are
further illustrated with e.g. surface plasmon resonance without
specifying what is meant.
All patent applications and issued patents cited in this
specification are incorporated by reference.
BRIEF SUMMARY OF THE INVENTION
During the last years we have come to the conclusion that it would
be beneficial if one could monitor both a) reactions taking place
within the individual microchannel structures, and b) presence or
absence of liquid in microchannel structures of a microfluidic
disc, for instance filling and emptying desired parts or functional
units of a structure. We have also recognized that a detection
principle that could be used for both alternatives would be of the
greatest advantage because then the same detector unit might be
used for monitoring events of type (a) and type (b). Thus one of
the main objects is to design a detector arrangement comprising the
same detection principle for measuring .mu.M-concentrations of an
analyte and the presence or absence of a liquid in a microchannel
structure. The concentrations concerned are typically subintervals
within the range 10.sup.-3-10.sup.-12 M, for instance
.ltoreq.10.sup.-6 M or .ltoreq.10.sup.-9 M. Still further
objectives are to manage measuring even lower concentrations, such
as down to 10.sup.-12 M or down to 10.sup.-15 M or down to
10.sup.-18 M or lower.
It would also be beneficial if a detector principle/arrangement
meeting this demand only gives a signal when aligned with a
detection microcavity. In this way it would be possible to minimize
the need for a home mark on the disc, a separate home mark detector
outside the disc and means for keeping track of which detection
microcavity is aligned with the detector at a particular
moment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a-b give a schematic view of an arrangement according to the
invention. FIG. 1a is a side view and FIG. 1b is a view from
above.
FIGS. 2a-c illustrates two variants of discs/disc holders with
different constructs of detection windows. In FIG. 2a a detection
window is directed downwards and extends from the microfluidic disc
into a separate plate of the disc holder. In FIG. 2b-c a detection
window is fully integrated into the microfluidic disc.
FIG. 3 illustrates the beam paths within the innovative
arrangement.
FIGS. 4a-g illustrates schematically variants of microfluidic discs
according to the invention. For reasons of simplicity only one out
of many of the cells for measuring surface plasmon resonance
(SPR-MCs) of a disc is shown. FIG. 4a shows a variant with the
detection windows downwards. FIG. 4b shows a variant with a cell
for measuring surface plasmon resonance (SPR-MC) which has
detection windows both upward and downward combined with a SPR
detection unit on each of the upward and downward sides of the
disc. FIGS. 4c-g show variants in which the SPR surface is at an
angle relative to the plane of the disc that is equal to the
incident angle .theta..degree.. The light source (LS) and the light
detecting subunit (LDS) are placed on opposite sides of the
disc.
FIG. 5 illustrates a variant of accomplishing optical contact
between the disc holder and the microfluidic disc by the use of a
so-called opto-interface plate.
The first digit in the reference numerals relates to the figure
number. Parts that have the same function in different figures have
reference numerals in which the second and third digits are the
same.
DETAILED DESCRIPTION OF THE INVENTION
We have recognized that the objects given above can be complied
with if surface plasmon resonance (SPR) as defined herein is
utilized as the detection principle.
In one aspect the present invention is the use of a surface plasmon
resonance detector unit for detecting a substance that is present
in DMCs of individual microchannel structures of a microfluidic
disc. This also includes monitoring events taking place within the
detection microcavities.
In another aspect, the present invention is a detector arrangement
comprising a rotatable microfluidic disc and an SPR detection unit
arranged such that the signal obtained from the SPR detector unit
reflects a) the presence of a particular substance and/or b) events
taking place within detection microcavities (DMCs) of the
individual microchannel structures of the microfluidic disc.
In a subaspect, the present invention is a detector arrangement
(FIG. 1) that is characterized in comprising: A. An SPR detector
unit (101) that comprises an SPR illumination system (IS) (102), an
SPR light detecting subunit (LDS) (103), and a beam path going from
IS to LDS (104a and 104b). The beam path comprises an incident beam
path (ibp) (104a) and a reflected beam path (rbp) (104b). The
incident beam path (ibp) ends and the reflected beam path (rbp)
starts at an SPR surface (105). The SPR surface and the parts of
ibp and rbp that are next to the SPR surface is always a part of a
rotary member (106) according to item (B) below. B. A rotary member
(106) that comprises one or more microfluidic discs (107) and a
disc holder (108).
In the context of the present invention the incident angle
.theta..degree. is the angle between the optical axis of the
incident beam and the normal of the reflecting surface (in this
case a surface plasmon resonance surface=SPR surface).
A. The SPR Detector Unit
The surface plasmon resonance (SPR) measuring technique is
basically a differential refractive index detection. The
opto-physical phenomenon is well known and means that total
reflection from certain surfaces is attenuated for p-polarized
light in terms of incident angle and wavelength, The surfaces are
typically metallic and made for instance of gold, silver, aluminum
etc and will henceforth be called SPR surfaces or SPR layers. The
suitable thickness (X) of an SPR layer typically can be found
within the interval <1000 nm, such as <500 nm. in the
interval 10-1000 nm, and depends among others on the material in
the layer. Preferred intervals are 10-1000 nm, such as 10-500 nm,
20-400 nm, and 10-500 nm. For gold the optimal interval typically
is about 100 nm, i.e. found within the interval 100 nm.+-.50 nm,
such as 100 nm .+-.25 nm. The angle of reflection at which the
attenuation occurs depends on angel of incident light (=incident
angle), wave-length of the incident light, refractive index of the
incident medium i.e. the medium closest to the SPR layer on the
same side as the reflection is taking place, temperature, SPR
surface/layer (e.g. type of metal and thickness), refractive index
of the medium that is present closest to the SPR layer but on the
side opposite to the incident medium etc. For further details see
textbooks in the field.
Measuring cells utilizing SPR (SPR-MCs) are well known in the
field. They have been used for monitoring molecular events at the
surface of a microchannel containing a liquid. As illustrated in
FIGS. 2a-c, an SPR measuring cell typically comprises a detection
microcavity (DMC) (209) that is part of a microchannel structure
(210), an SPR surface/layer (205) in one of the inner walls of the
detection microcavity, and a detection window (DW) (211) that
extends from the SPR surface/layer away from the detection
microcavity. The detection window has one entrance surface (212a)
for the incident light beam and one exit surface (212b) for the
light beam (213) reflected in the SPR-surface (205). The medium to
be analyzed is typically a liquid and is present in the detection
microcavity (DMC).
By utilizing p-polarized light comprising a range of incident
angles and keeping all other variables constant except for the
medium in the detection microcavity, this kind of cells has been
used for monitoring changes in refractive index that are taking
place at the SPR surface within the detection microcavity.
Typically, the side of the SPR layer in direct contact with the
medium to be analyzed carries an immobilized affinity reactant and
the medium contains a diffusible affinity counterpart to this
affinity reactant. Upon formation of an affinity complex on the SPR
surface, the refractive index of the medium next to the SPR surface
will change which leads to a change in the angle at which
attenuation of reflection occurs. From this change, possibly in
combination with a standard curve or calibrator substances/values,
it is possible to determine features of the diffusible affinity
counterpart. An immobilized affinity reactant is not required, if
the SPR measuring cell is to be used for measuring the presence or
absence of a liquid.
The illumination system (IS) illustrated in FIG. 3 comprises the
appropriate light source (LS) (302) with the appropriate beam path
arrangement for focusing light on the SPR surface (305) via the
detection window (311) (e.g. with a lens system (314a), and/or
filters (316), and/or mirrors (315a) etc. In order to accomplish a
sharp attenuation the illumination system should give
mono-chromatic p-polarized light, typically selected with a
wavelength within the interval of 1-1000 nm, such as 500-900 nm or
350-1000 nm, and with preference for 600-800 nm. The mean incident
angle .theta..degree. is typically found in the interval of
45.degree.-85.degree., in particular 55.degree.-80.degree., such as
62.degree.-72.degree. (relative to the normal of the SPR surface).
The light used may comprise a range of incident angles typically
covering .ltoreq.10.degree., such as .ltoreq.5.degree. or
.ltoreq.4.degree., and .gtoreq.0.5.degree., such as
.gtoreq.1.degree. or .gtoreq.2.degree.. The light beam reaching the
SPR surface typically should be wedge-shaped or conical and
comprise a mixture of incident angles within the ranges given. In
alternative variants the range of incident angles is achieved by
changing the incident angle during the measurement, for instance by
moving the illumination system in relation to the SPR surface.
Monochromatic light in the context of the invention means light
with a band-width in the interval 0-30 nm, such as 0-5 nm or 0-3
nm.
The light detecting subunit (LDS) (303) that also is illustrated in
FIG. 3 is capable of determining at which angles the reflected beam
is attenuated. Thus this subunit may comprise a photodetector array
or any other suitable means (317) for detection of the reflected
light, and the appropriate arrangement containing the necessary
items for focusing the reflected light on the photodetector means
(317) and placed at a position where it can collect and
discriminate light of different reflection angles defined by the
range of incident angles. Typically the necessary items include a
lens system (314b) and possibly also a mirror (315b). Alternatively
the photodetector part of the LDS only detects light of one
reflection angle at a time but is movable relative to the SPR
surface during the measurement so that it will collect light
corresponding to the range of the angles of reflection.
The SPR principle has been outlined in a number of textbooks and
review articles, including details about the illumination system,
SPR measuring cells, and light detecting subunits, optics, incident
angles, wavelengths etc. See for instance Nagata et al., "Real-Time
Analysis of Biomolecular Interactions", "Part 2 General
principles", Springer-Verlag, Tokyo, Japan (2000) pages 13-30. See
also Patents Abstract of Japan, Volume 2000, No 2, Nov. 5, 2000
& JP 11 304693 A (Matsushita) and WO 0046589 (Vir A/S).
As illustrated in FIGS. 2a-c, the incident beam path (ibp) (204a)
starts at the illumination system (202) and passes into a detection
window (211) via an entrance surface (212a) of the detection
window, and ends at the SPR surface (205). The reflected beam path
(rbp) (204a) starts at the SPR surface (205), leaves the detection
window (211) via the exit surface (212b) of the detection window
(211), and ends at the light detecting subunit (LDS) (203). Ibp and
rbp (204a and 204b, respectively) never pass through the medium to
be analyzed.
The SPR detector unit is typically non-rotatable about the axis of
rotation of the rotary member. The unit may in preferred variants
be laterally movable such that the intersection of ibp and rbp
radially can transverse the surface of the rotary member in which
the detection windows are exposed.
The plane defined by the incident beam path and the reflected beam
path is typically orthogonal to the plane of the disc/rotary
member. Relative to the radius of the disc/rotary member, the same
plane may in principle have any direction, for instance parallel or
orthogonal. It can be envisaged that increasing the angle between
this plane and the radius would give more space for the SPR
detection unit and therefore be more preferred. Accordingly, an
essentially orthogonal arrangement, for instance within
.+-.45.degree., such as within .+-.15.degree., are many times
preferred. FIGS. 1-2 and 4a-e illustrate variants in which the beam
path is parallel to the radius of the rotary member. In FIGS. 4f-g
the arrangement is orthogonal.
B. The Rotary Member
This part will mainly be described with reference to FIGS. 1-2. The
rotary member (106,206) has an axis of rotation (117) and comprises
a disc holder (108,208) and one or more microfluidic discs
(107,207). The disc holder typically is mounted on a spindle that
is linked to a shaft of a rotor motor schematically shown as (118).
The rotary member typically has an axis of symmetry (C.sub.n)
coinciding with the axis of rotation (117) and being perpendicular
to the plane of the rotary member. n in C.sub.n is an integer 2, 3,
4, 5 or more with preference for n.gtoreq.6, 7, 8 and .infin.
(C.sub..infin.=circular). The disc holder (208) may comprise a
separate plate (219) between a plate holder (220) and the
microfluidic disc (207) (see FIG. 2a).
The terms "radial distance" or "radial position" will henceforth
refer to the shortest distance between an object and the axis of
rotation.
The rotary member (106,206) is typically disc-shaped with three
sides: the spindle side (221a), the side opposite to the spindle
side (221b), and the edge side (221c). In the case there is a
central hole for holding the disc in the disc holder there is also
a forth side defining the hole. Since this side is occupied by
retaining the disc in the disc holder this fourth side is not
counted. The edge side is at the circumference of the disc-shaped
rotary member. In a similar manner a microfluidic disc has three
sides: the disc holder side (222a), the side opposite to the
disc-holder side (222b) and the edge side (222c). The spindle side
of the rotary member and the disc holder side of the disc will be
called the lower side or the downward side. The opposite side will
be called the upper side or the upward side. This terminology is
irrespective of their orientation relative to the ground.
The rotary member comprises a number of SPR measuring cells
(SPR-MCs) of the type defined above. The detection microcavity
(DMC) and the SPR surface of an SPR-MC will typically always be
part of the microfluidic disc. A detection window will have one
part (P1) (211a) that is fully integrated into the microfluidic
disc, and a possibly second part (P2) (211b) that is part of the
disc holder (208). P1 extends from the SPR surface away from the
detection microcavity (209,409) to the outer surface of the
microfluidic disc. P2, if present, is in optical contact with P1,
preferably via an opto-interface (223). See FIGS. 2a and 6.
The rotary member always contains a group of SPR-MCs (first
plurality) that are at the same radial distance and with entrance
surfaces and/or exit surfaces on the same side of the rotary
member. This in most cases means that the parts P1 of the detection
windows of these SPR-MCs end on the same side of the microfluidic
disc, for instance in the upper or the lower side.
There may also be present another group of SPR-MCs (second
plurality) that are oriented with entrance surfaces and/or exit
surfaces to the same side as the first plurality but positioned at
radial distances that are different from the radial distance of the
SPR-MCs of the first plurality.
There may also be present a third group of SPR-MCs (third
plurality) which is characterized in that their entrance surfaces
and/or their exit surfaces are at a side of the rotary member that
is different from the side carrying the corresponding surfaces of
the first and second pluralities. The third plurality may comprise
one subgroup of SPR-MCs that are located at the same radial
distance and another group for which the SPR-MCs are located at
other radial distances. The third group may have its entrance
and/or exit surfaces at the lower or the upper side of the disc
depending on which side is occupied by the corresponding surfaces
of the first plurality of SPR-MCs.
The radial distances discussed for the SPR-MCs primarily refer to
the radial distances of the entrance and/or exit surfaces of the
detection windows.
The SPR-MCs including the SPR surfaces, detection windows,
detection microcavities and the entrance and exit surfaces may be
arranged as one, two or more concentric circles around the axis of
rotation and/or in a spoke arrangement with the axis of rotation as
the center. See FIG. 1b where there are two concentric circles
(125a and b) of detection windows (111) on the lower side of the
disc. The corresponding detection microcavities and microchannel
structures are completely inside the disc and therefore not
visible.
The detection microcavities may be arc-shaped or straight and
essentially parallel to the periphery of the disc. Also other
directions are possible, such as perpendicular to the periphery of
the microfluidic disc (i.e. radial direction) and/or any other
intermediary direction that might be defined by the individual
microchannel structures of the microfluidic disc.
The optical axis of the incident and reflected beam paths are
typically essentially orthogonal to the entrance and exit surfaces,
respectively, of a detection window. This means that an entrance
surface and an exit surface typically should be oriented relative
to an SPR surface at angles that are essentially the same as the
incident angle, i.e. +.theta..degree. and -.theta..degree.,
respectively. See the figures.
The SPR surfaces are in many variants essentially parallel to the
plane of the microfluidic disc, i.e. perpendicular to the axis of
rotation.
In certain innovative arrangements there may be one, two or more
SPR surfaces that are oriented relative to the plane of the disc at
an angle that is >0.degree. but <90.degree.. In the case that
the angle between the SPR surfaces and the plane of the disc may be
equal to or close to equal to the incident angle .theta..degree.,
either the incident beam path or the reflected beam path may be
essentially parallel to the axis of rotation. This is illustrated
fin FIGS. 4c-g in which the SPR surface (405) is in a sloped
sidewall of the detection microcavity (409). One can envisage that
this might a) simplify the way of configuring the illumination
system and the light detecting subunit in the arrangement (as
illustrated in FIGS. 4c-g), and/or b) reduce the demand on
planarity and the negative effect wobbling might have in the case
measurement is done while spinning the rotary member.
By rotating the rotary member around the axis of rotation, it will
be possible to replace the parts of ibp and rbp that are within a
particular SPR-MC with the corresponding parts of any other of the
remaining SPR-MCs that are within the same radial distance. By
laterally moving the SPR detector unit and/or the rotary member, it
will be possible to replace the parts of ibp and rbp of SPR-MCs
that are at different radial distances but at the same angular
position with each other. By combining rotation and lateral
movement, the SPR-MCs can replace each other independent on their
radial or angular position. These general rules apply provided all
the detection windows are oriented in the same way relative to the
plane of the microfluidic disc.
B.1. The Microfluidic Disc
Typically there is only one disc associated with a disc holder in
the rotary member but as described below there may be also two,
three or more.
A microfluidic disc that is to be used alone in the rotary member
typically has an axis of symmetry (C.sub.n) that is perpendicular
to the plane of the disc. When the disc is placed in the disc
holder this axis of symmetry coincides with the axis of rotation of
the rotary member. n in C.sub.n is an integer 2, 3, 4, 5 or more,
with preference for n.gtoreq.6, 7, 8 . . . .infin. (C.sub..infin.).
The circular disc form (C.sub..infin.) is preferred.
In variants where two or more discs are used simultaneously in the
same disc holder they are typically placed without overlap therein.
Discs that are to be used simultaneously should have the same
geometric form and be placed symmetrically around the axis of
rotation. Examples of geometric forms are: sector-like,
rectangular, oval etc.
A microfluidic disc comprises a plurality of essentially equal
microchannel structures that are enclosed within the disc. In each
of the microchannel structures one or more reactants are to be
transported between two, three or more functional units by a liquid
flow. The liquid flow in turn is, according to the invention,
typically driven by inertia force, for instance centrifugal force,
and/or capillary force. Other forces may alternatively be used or
combined with these kinds of forces. The term "reactant" includes
analyte. The reactants and/or the liquid aliquots as such are
typically processed in a microchannel structure, and the result of
the processing is determined in a detection microcavity (DMC) that
typically is positioned in a downstream part of the microchannel
structure, i.e. downstream an inlet port. Typical functional units
in addition to DMCs are volume defining units, transport channels,
units for separating particulate matters, units for separation
based on affinity for a ligand that is attached to a solid phase,
mixing units, units for performing chemical reactions such as
enzyme reactions, affinity reactions etc, valves etc. Each
microchannel structure starts at an inlet port for liquid, passes
one or more functional units of the types given above and ends in
an outlet port that may be for liquids and/or air (outlet air
vent). There may be additional inlet ports and outlet ports. Such
ports may be for liquids and/or air (inlet and outlet vents,
respectively). An inlet port or an outlet port may be common for
two, three or more microchannel structures. The presence of a
plurality of microchannel structures enables timely parallel
transport and processing of liquid aliquots and reactants that have
been dispensed to inlet ports.
Each microchannel structure may comprise one, two or more detection
microcavities (DMCs) of the kind defined above.
The ports may be located to the same side or to different sides of
the microfluidic disc. Typically inlet ports for liquids are
located to the upper side of the disc. In the case that ports are
located to the lower side of the microfluidic disc it becomes
important to secure that the disc holder provide unhindered access,
for instance to ambient atmosphere, around these kinds of openings
for their proper functioning.
In order to use centrifugal force for driving a liquid flow within
a microfluidic disc, the disc should be a) spinnable around the
axis of rotation, and b) each microchannel structure should have an
upstream part that is at a shorter radial distance from the axis of
rotation than a downstream part,
when placed in the disc holder of the present innovative
arrangement. This in many cases means that each microchannel
structure has an inlet port at a shorter radial distance than one
of the functional units, e.g. an outlet port or a detection
microcavity. The outlet port may be an outlet for liquid.
Centrifugally based microfluidic discs with microchannel structures
and measurement cells to be used for detection principles other
than SPR have been disclosed in a number of scientific articles and
patent publications. The microfluidic principles then outlined
could typically be used also in the present invention except that
the cells for measurement have to be adapted to surface plasmon
resonance. Centrifugally based microfluidic platforms have been
described in WO 03025548 (Gyros AB), WO 02075312 (Gyros AB), WO
02075775 (Gyros AB), and WO 02075776 (Gyros AB), WO 9721090 (Gamera
Bioscience), WO 9807019 (Gamera Bioscience) WO 9853311 (Gamera
Bioscience), WO 9955827 (Gyros AB), WO 0040750 (Gyros AB), WO
0147638 (Gyros AB), WO 0146465 (Gyros AB), U.S. Pat. No. 5,160,702
(Molecular Devices Corp,), U.S. Pat. No. 5,472,603 (Abaxis)
etc.
The term "plurality" in the context of the invention contemplates
two, three or more of an item (e.g. microchannel structures,
SPR-MCs etc). Thus plurality may mean .gtoreq.10 or .gtoreq.25 or
.gtoreq.50 or .gtoreq.100 or .gtoreq.200 essentially equal items,
e.g. microchannel structures. For microchannel structures the term
"plurality" typically contemplates 96, 384, 1536, etc structures,
possibly plus .ltoreq.10% of excess structures in order to secure
that one microchannel structure per well of a microtitre plate is
available. Excess structures are also called redundant structures
and may be present also in larger numbers. See for instance WO
030872730 (Gyros AB) and corresponding U S application
20030211012.
The terms "microchannel", "microconduit", "microformat" etc
contemplate that a) a microchannel channel structure comprises one
or more cavities and/or channels/conduits that have a
cross-sectional dimension that is .ltoreq.10.sup.3 .mu.m,
preferably .ltoreq.10.sup.2 .mu.m, and/or b) the volumes of the
microcavities/microchambers and/or the liquid aliquots to be
processed are in the .mu.l-range, i.e. .ltoreq.1000 .mu.l such as
.ltoreq.100 .mu.l or .ltoreq.50 .mu.l including the nl-range
(nanoformat), such as .ltoreq.5000 nl or .ltoreq.1000 nl or
.ltoreq.500 nl or .ltoreq.100 nl or .ltoreq.50 nl.
The microfluidic disc is typically manufactured from two planar
substrates, at least one of which is microstructured in one of its
sides in such a manner that the microchannel structures of the
final microfluidic disc are formed when joining the microstructured
side of one substrate with a possibly microstructured side of the
other substrate. Either one or both of the substrates may have
through-going holes that are associated with individual
microchannel structures in the final microfluidic disc. These holes
may be used as ports, i.e. inlets or outlets for liquids and/or as
inlet or outlet vents for air.
Inorganic and/or organic material constitute an essential part of
the substrate. Typical inorganic materials are silicon, quartz,
glass etc. Typical organic materials are polymer materials, for
instance plastics including elastomers, such as rubber silicone
polymers (for instance poly dimethyl siloxane) etc. Suitable
polymer materials and plastics typically comprise polymers that are
obtained by addition polymerization, condensation polymerisation,
polymerisation of unsaturated organic compounds etc. The
microstructures may be created by various techniques such as
etching, laser ablation, lithography, replication by embossing,
moulding, casting etc, etc.
Substrates that expose surfaces and microstructures in plastics are
many times preferred because the costs for plastics are normally
low and mass production can easily be done. See for instance WO
9116966 (Pharmacia Biotech AB, Ohman & Ekstrom). By using
plastics for the manufacture the microfluidic discs may become
disposables. At the priority date of the present invention, the
preferred plastics were transparent with a refractive index
typically within the interval of 1.45-1.55. Typical examples are
plastics that comprises polyolefins obtained by polymerization of
monomeric olefins in which there is a straight, branched, and/or
cyclic aromatic or non-aromatic structure, e.g. Zeonex.TM. and
Zeonor.TM. from Nippon Zeon, Japan. This does not outrule the use
of other transparent plastics having acceptable refractive index
and potentially comprising polycarbonates, polystyrenes,
polymethacrylates and/or the like. This selection criterion based
on refractive index in particular applies to substrates that
contain the parts P1 of the detection windows.
The entrance and/or the exit surfaces with the appropriate angles
relative to the plane of the disc may be introduced in the form of
prism surfaces by replication against a surface carrying the
inverse microstructure. Alternatively, one can envisage that prisms
with the appropriate surfaces may be separately attached either
before or after the substrates have been joined together.
There are a number of techniques for joining the two substrates
together. See for instance WO 9424900 (Ove Ohman), WO 9845693
(Soane et al), U.S. Pat. No. 6,176,962 (Soane et al), WO 9956954
(Quine), WO 0154810 (Derand et al), WO 9832535 (Lindberg et al), WO
0197974 (Chazan et al), and WO 03055790 (Gyros AB) and
corresponding U S application 20030129360.
Before joining the two substrates together the SPR surface/layer is
locally introduced at detection window positions of surface parts
that are to become inner walls in the final device, i.e. in an
uncovered microstructure and/or in a flat part of the surface of
the opposite substrate.
The microfluidic disc described above in which centrifugal force
can be used for creating a liquid flow in each of one, two or more
of the microchannel structures constitute a subaspect of the
invention. The flow is capable of transporting reactants from an
upstream functional part to a downstream functional part.
Accordingly the present invention provides a microfluidic disc
(107,207,307,407, 107) having an axis of symmetry (117,417) as
discussed above and comprising a plurality of microchannel
structures, each of which has an upstream functional part that at
least partly is at a shorter radial position than a downstream
functional part and in fluid communication with said downstream
functional part. This disc is characterized in that there are
detection microcavities (DMCs) (209,309,409) in at least a part of
said microchannel structures and that each of said DMCs has an SPR
surface (205,305,405) on an inner wall. The inner wall (detection
window) (211,311,411) extending from the SPR surface to the surface
of the disc is in a material that is translucent for light normally
contemplated for surface plasmon resonance. Materials and designs
of SPR surfaces and inner walls between the SPR surface and the
surface of the disc are as discussed elsewhere in this text.
This subaspect also comprises that the microfluidic disc is
combined with a disc holder plate (219) comprising the remaining
parts P2 (211b) of the detection windows (211) if they are
incomplete in the microfluidic disc. This subaspect also comprises
that an opto-interface plate is combined with the microfluidic disc
and the disc holder plate (219). For disc holder plate and
opto-interface plate see elsewhere in this specification.
FIGS. 4a-g illustrate three variants of microfluidic discs in which
the complete detection window (411) including the SPR surface (405)
and the entrance surface (412a) and the exit surface (412b) are
part of the disc. The figures have been simplified showing only one
of the SPR-MCs/microchannel structures in enlarged form. The axis
of symmetry (axis of rotation) has been indicated (417) in some of
the figures. The light source (402) with incident beam path (404a)
and light detecting subunit (403) with reflected beam bath (404b)
are in principle interchangeable. The plane defined by the incident
beam (404a) and the reflected beam (404b) is for the variants of
FIGS. 4a-e aligned radially and for the variants of FIGS. 4f-g
orthogonal to the radius of the microfluid disc. The portions of
the microchannel structure that are upstream and downstream the
detection microcavity (409) in FIGS. 4a-c are not visible because
these portions are not at the same angular position as the
detection microcavity. The detection microcavity (409) is
essentially parallel to the circumference of the disc.
FIGS. 4a-b illustrate variants in which the SPR-surface is
essentially parallel to the plane of the disc and the entrance
surface (412a) and the exit surface (412b) essentially at the
angles -.theta..degree. and +.theta..degree. relative to the disc
plane (i.e. the same as incident angle/reflecting angle).
FIGS. 4c-g illustrate variants in which a) the SPR surface is
essentially at the angle .theta..degree. relative to the plane of
the disc, b) the entrance surface (412a) essentially parallel to
the disc plane and c) the exit surface (412a) essentially at the
angle .theta..degree.. The incident beam is orthogonal to the plane
of the disc.
FIGS. 4d-e illustrate a variant of a disc in which there is a
peripheral detection microcavity (409) which is essentially
parallel to the circumference of the disc. FIG. 4d is a
cross-sectional view of the disc along a plane which is
perpendicular to the plane of the disc and passes through the
center (axis of rotation) (417), a detection microcavity (409) and
the edge (426) of the disc. FIG. 4e is a view seen from above of an
outer part of a sector of the disc surrounding said plane. The
cross-sectional area (427) of the detection microcavity (409) is
triangular. The detection microcavity (409) is part of a
microchannel (410) that in the downstream direction is ending in an
outlet (428) placed in the circumferential edge (426) of the disc.
The SPR surface (405) is angled relative to the plane of the disc
such that the incident beam (404a) is orthogonal to the plane of
the disc. The upper part of the circumferential edge (429) is
sloped at least at the position of the surface of the detection
window (411) such that the reflected beam (404b) will leave through
the exit surface (412b) orthogonally. The light source (402) and
the light detecting subunit (403) are placed on different sides of
the disc.
FIGS. 4f-g illustrate a variant with an elongated detection
microcavity (409) that is aligned radially and part of a
microchannel (410) that ends in the circumferential edge (426) of
the microfluidic disc (407). The microchannel part shown coincides
with the detection microcavity. FIG. 4f is an edge-view of a sector
(430) of the disc. FIG. 4g shows the same sector (430) seen from
above with the upper substrate (431) removed and the lower
substrate exposed (432). The cross-sectional area of the detection
microcavity (409) and the configuration of the SPR detector are
similar to the variant illustrated in FIGS. 4d-e. Since the exit
surface (412b) in this variant is not placed in the edge of the
circumference, there is a separate groove (434) in the lower
substrate (432). This groove (434) is parallel to the detection
microcavity (409) and provides the exit surface (412b) angled
appropriately relative to the reflected beam path (404b). The upper
substrate (431) then comprises a corresponding through-passing
opening (435) that also is elongated and parallel to the detection
microcavity (409). The light source (402) and the light detecting
subunit (403) are placed on different sides of the disc. The
configuration leaves good space for radial movement of SPR detector
unit.
B.2. The Disc Holder
The disc holder will be described in reference to FIGS. 1, and
2a-c. The disc holder (108,208) is part of the rotary member (106)
and is attached to a spindle, which in turn is connected to a shaft
of a motor schematically shown as (118). The motor is capable of
rotating the shaft, spindle and rotary member around a common axis
of rotation (117). The disc holder has an axis of symmetry as
discussed above for the rotary member and provides essentially
planar support for a microfluidic disc (107,207)) that is seated on
the rotary member (106,206). This includes that the rotary member
is disc-shaped, comprises spokes extending radially outwards from
the axis of rotation etc. If the rotary member provides a
disc-shaped surface to support the microfluidic disc it may contain
openings passing through the disc. These kinds of openings may be
used for the beam path to reach detection windows that are located
in the lower side of a microfluidic disc, and for providing
subpressure to retain the disc in the disc holder, for
instance.
In order for the detector arrangement to work properly it is
important that the disc holder defines a support plane of
sufficient planarity for the microfluidic disc(s). This in
particular applies if the disc(s) is/are made in plastics and
easily are skewed. The support plane is primarily defined by the
local areas in the disc holder that are to be contacted with local
areas in the lower surface of the microfluidic disc. Typically the
most important local areas of the disc in this context is in close
association with the parts P1 of the microfluidic disc. This demand
for planarity becomes particularly stringent when high sensitivity
is required, e.g. when determining features of an analyte that is
present in the concentration ranges outlined under the heading
"Objects of the Invention". Accordingly, the support plane
typically has a planarity, which is dependent on use and has been
selected in the interval 0-100 .mu.m. When looking for increased
sensitivities the selection has to be made in more narrow
subintervals, such as .ltoreq.50 .mu.m or .ltoreq.25 .mu.m or
.ltoreq.10 .mu.m or .ltoreq.5 .mu.m or .ltoreq.2 .mu.m. The support
plane is typically defined by a disc-shaped plate fabricated in
glass, steel or any other rigid material that is able to provide
surfaces of a high degree of planarity. Spoke arrangements and
other arrangement in forms that is capable of defining support
planes of sufficient planarity (discontinuous contact area) may
also be used.
There exist a number of different ways for firmly holding the
microfluidic disc on the disc holder. One alternative means that
the disc holder has holding means for the center and/or the
periphery of the microfluidic disc. In preferred variants and in
particular if characterization of analytes in microfluidic discs
made in plastics is concerned, it can be envisaged that an evenly
applied subpressure through the disc holder against the
microfluidic disc will promote planarity. To accomplish this a
vacuum source may be connected to a non-rotatable part of the
arrangement for providing sub-pressure to a) openings, b) a system
of microchannels etc that are present in the support surface of the
disc holder. A system of microchannels in this context also
comprises an evenly roughened form of the support surface, e.g.
blasted. These openings and channel systems may be evenly
distributed across the top surface of the disc holder, but it is
often more important to secure equal subpressure adherence to the
lower surfaces of the disc close to or at the positions of the
SPR-MCs. Utilizing sub-pressure in the context of rotatable
substrates in microfluidic discs has been described in WO 03025449
(Gyros AB) and U S 20030082075.
The disc holder may be designed as a cassette in which two or more
discs are place more or less side by side. In this variant there
may be separate positioning means for each disc. Thus the rotary
member may provide fixation means that fit to the form of each
individual disc. If the rotary member provides a more or less
continuous support surface the fixation means may be in the form of
a depression matching exactly the disc. There may also be
adjustable means such as pins, clamps or the like permitting
different forms of discs to be seated in the disc holder. It is
important that the discs are placed symmetrically on the disc
holder in order not to imbalance the rotary member if higher
spinning speeds are to be used for creating liquid flow within the
disc or for measuring with the SPR detector unit while spinning,
for instance. Subpressure may also be used.
The entrance and exit for radiation to/from may be on any side of
the microfluidic disc (107,207), i.e. the upper, lower and/or edge
side. Typically, however, entrance and exit are via the lower or
the upper side, i.e. on the opposite or on the same side as the
disc holder. In the latter variants it is important that the disc
holder does not hinder passage of light in ibp and rbp. Therefore
the disc holder may provide channels and/or other free spaces (124,
224) going from the entrance and exit surfaces (212a and 212b,
respectively) to the lower surface of the disc holder.
Alternatively, the detection windows may extend downward through
the disc holder without need for this kind of channels.
As discussed above the disc holder (108,208) may comprise a part P2
(211b) of the detection windows (211) provided the detection
windows and the disc holder are on the same side of the
microfluidic disc. An illustrative example is that the disc holder
comprises a separate plate (219) (disc holder plate) of
sufficiently high planarity and have a size providing support for
the disc(s) that is/are placed in the holder (as discussed above).
In addition to the disc holder plate, the disc holder then also
comprises a plate support holder (220), which provides for the
channels and the empty space (124,224) through which ipb and rpb
are passing. The disc holder plate (219) typically is made of a
material that a) has essentially the same optical properties
(refractive index) as the detection windows for the light from the
light source, and b) carries on its lower side the entrance and
exit surfaces that match the parts P1 of the detection windows of
the microfluidic disc.
The entrance and exit surfaces may be in the form of the prism
surfaces.
In order for light to pass across the interface between P1 (211a,
FIG. 2a) and P2 (211b, FIG. 2a), an opto-interface (223, FIG. 2a)
is placed between P1 and P2 for each of the detection windows that
comprise both P1 and P2. The techniques for creating appropriate
opto-interfaces for SPR measurements are well known in the field.
See for instance U.S. Pat. No. 5,164,589 (Biacore AB) and WO
9719375 (Biacore AB). Typical materials for opto-interfaces are in
the form of oils (immersion oils), or more preferably in form of
optical transparent elastic material (opto-interface gel) that
should have essentially the same refractive index as the material
in P2 and P1. Suitable material may be selected amongst transparent
rubbers or elastomers that may be cross-linked to various degrees,
and transparent epoxy resins. Useful materials are commercially
available.
In a preferred variant (FIG. 5) the opto-interface material is part
of plate (536) (opto-interface plate), which is placed between the
top surface of the disc holder (508) and the microfluidic disc
(507). At the position of each detection window (511) this plate
exposes an opto-interface material (523a,b) to both P1 and P2 when
the opto-interface plate (536) is properly aligned in the disc
holder. In other words the plate exposes an opto-interface material
on both sides of the opto-interface plate at least at the positions
that are to be aligned with P1 and P2 of a detection window.
The opto-interface plate may comprise a continuous support plate
(537, opto-interface support plate) of translucent material of
essentially the same refractive index as P1 and P2. The
opto-interface material (538), preferably an opto-interface gel, is
then placed on the upper and lower sides of the opto-interface
support plate (537) and covers at least the positions of the
detection windows.
In one variant the opto-interface material is localized to parts of
each of the upper and lower sides of a continuous opto-interface
support plate (537) (FIG. 5). The pattern of the opto-interface
material is such that it will provide optical contact for P1 and P2
in each detection window. Each piece of opto-interface material may
cover one two, three or more detection windows and is typically
thicker in the center of each piece, for instance dome-shaped or
stepped as suggested in U.S. Pat. No. 5,164,589 (Biacore AB) and WO
9719375 (Biacore AB). The material may be in form of ridges that
may cover arc-shaped, rectangular-shaped etc subareas on the upper
and/or lower side of the opto-interface plate (537). The material
may be arranged as one two or more continuous or discontinuous
annular concentric rings around the center (axis of rotation) of
the disc.
In another variant the opto-interface material forms a continuous
layer on either one or both of the sides of an opto-interface
support plate (537), possibly with raised parts at the detection
windows in analogy with what has been discussed for the first
variant.
In still another variant the opto-interface support plate (537)
have through-passing holes in which the opto-interface material,
typically in the form of an elastic material is placed.
In still another variant the opto-interface plate is moulded in an
opto-interface material.
The opto-interface plate (536) is placed in the disc holder with
the opto-interface material matching the parts of the detection
windows in the microfluidic disc (507) and the plate (519) (parts
P1 (511a) and P2 (511b), respectively). When pressed together the
shape and elasticity of the opto-interface material will assist in
avoiding inclusion bubbles of air that may adversely affect the
optical properties of the opto-interface.
Further information on the selection and shape of the
opto-interface material is found in U.S. Pat. No. 5,164,589
(Biacore AB), WO 9719375 (Biacore AB) and other publications in the
field.
In case subpressure is used for retaining the microfluidic disc in
combination with an opto-interface plate, there should be channels
(539, subpressure channels) or openings providing subpressure from
the disc holder.
It is beneficial that the various parts of the rotary member such
as the disc holder/plate holder, opto-interface plate, plate
carrying P2 parts of detection windows, microfluidic disc(s) etc
comprises guiding means that facilitates proper alignment of the
parts P1, parts P2 and channels and open spaces in the disc holder
both before, after or during rotation/spinning of the rotary
member. Guiding means may be physical, for instance in forms of
matching indentations, pins, holes etc, or adaptive and controlled
by software. The latter may be illustrated by automatically
adjusting the alignment between the microfluidic disc and the parts
of the beam paths in the disc holder as a function of the signal
obtained by an SPR detector unit before the different parts are
firmly clamped to each other, for instance by applying
subpressure.
Other Parts of the Detector Arrangement
As discussed above the innovative arrangement comprises a motor
(rotor motor) that is capable of rotating the rotary member for
position SPR-MCs of the same radial distance (first plurality) in
front of the intersection between ibp and rpb. The motor should
permit stepwise rotation enabling measurement in an SPR-MC each
time ibp and rbp are complete and the incident beam targets an SPR
surface. One can also envisage measurement during continuous
spinning, possibly combined with intermittent measurement each time
the incident beam is able to target an SPR surface.
The rotor motor preferably should permit a wide range of rotation
speeds, for instance from 0 up to 15 000 or 20 000 or 30 000 rpm or
even faster. The motor should permit stepwise rotation and/or
continuous spinning or rotation, and optionally be regulatable.
This will enhance the versatility of the innovative arrangement
since a) spinning may be used to create sufficient centrifugal
force for driving liquid flow in parallel within the individual
microchannel structures of the disc(s) and b) measurement of the
various SPR-MCs can be performed.
Spinning for driving liquid flow and rotating/spinning for
measurement may be done with the same rotor motor or with different
rotor motors. If different motors are used the microfluidic disc is
typically transferred to the appropriate motor arrangement before
the particular operation is performed.
As discussed above the rotary member may also contain SPR-MCs
(second plurality) that are at radial distances that are different
from those of the first plurality. In these variants the rotary
member and/or the SPR detection unit is/are linked to a
translational responder for incremental changing the radial
position of the SPR detector unit (in fact the intersection between
rbp and ibp) thus enabling measurement in the SPR-MCs of the second
plurality.
In the case both the first and the second plurality of SPR-MCs are
present in the rotary member the two motors may be coordinated so
that measurements are carried out in all or in a predetermined
subgroup of the SPR-MCs. The possibility of measuring will become
independent of radial and angular positions of the SPR-MCs.
The measurement is typically under control of a controller
comprising the appropriate software and hardware.
The control of the alignment of the SPR detector unit with the
SPR-MCs and/or measurement are following general principles known
in the field for other detection principles. Particularly
advantageous methodologies are disclosed in WO 0325548 (Gyros AB)
and U S 20030054563 (GYROS AB) and WO 03087779 (Gyros AB) and
corresponding U S application 20030231312. In certain variants the
motors are equipped with a suitable encoder that for the rotor
motor may be associated with the shaft, spindle or the rotary
member, with preference for the last one.
The Use of the Innovative Detector Arrangement.
The use comprises a) determining the presence or the absence of a
liquid and/or b) determining an uncharacterized feature of an
analyte in at least one of the detection microcavities of a
microfluidic disc, which is part of the rotary member of the
arrangement described above.
The use corresponds to a method comprising the steps of: i)
providing the detection arrangement described above in which
liquids have been introduced into one or more of the microchannel
structures, and ii) determining whether or not liquid has entered
one or more predetermined detection microcavities, and/or if an
analyte is present in one or more detection microcavities of the
microchannel structures int which liquid has been introduced.
The SPR detector unit may also be used for proper
matching/alignment the different parts of the rotary member to each
other so that the incident beam can reach the SPR-surface and the
reflected beam can reach the light-detecting subunit (LDS), or for
keeping track of SPR-MCs that are in front of the SPR detector
unit.
The liquid may be water or an organic solvent or a mixture of these
kind of solvents. Typical liquids are aqueous. The analyte, i.e.
the molecular entity to be detected by the SPR measurement, may be
an affinity reactant which is capable of binding to an affinity
counterpart that is immobilized to the SPR surface (inside the
SPR-MCs). Also other analytes may be determined/monitored in the
detection microcavities of the innovative arrangement provided the
binding of the analyte to the SPR-surface changes the refractive
index of the liquid next to the surface.
General Statement
Certain innovative aspects of the invention are defined in more
detail in the appending claims. Although the present invention and
its advantages have been described in detail, it should be
understood that various changes, substitutions and alterations can
be made herein without departing from the spirit and scope of the
invention as defined by the appended claims. Moreover, the scope of
the present application is not intended to be limited to the
particular embodiments of the process, machine, manufacture,
composition of matter, means, methods and steps described in the
specification. As one of ordinary skill in the art will readily
appreciate from the disclosure of the present invention, processes,
machines, manufacture, compositions of matter, means, methods, or
steps, presently existing or later to be developed that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present invention. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
* * * * *